1. Field of the Invention
The invention relates to data encryption and decryption, and more particularly to a method and system for locally activating a DRM engine.
2. Description of the Related Art
Data delivery comprises on-line delivery and off-line delivery. The on-line delivery process downloads digital content via the internet. The off-line delivery process preloads digital content in a specific storage medium, such as a compact disc (CD), a digital versatile disc (DVD), or a flash memory device (like a secure digital (SD) card or a universal serial bus (USB) disc) of a portable electronic device (such as a mobile phone).
The off-line delivery process can be protected using a Content Scrambling System (CSS) for DVDs and a Content Protection for Recordable Media (CPRM) or a Content Protection for Pre-recorded Media (CPPM) for SD cards and DVD-RW.
Digital content must be processed using a digital rights management (DRM) system to be protected from illegal use or pirating.
FIG. 1 is a flowchart of a conventional method for DRM processing.
Preprocessed digital content files are stored in a file server on the internet (step S11). For an authorized user, permissions or rights objects are acquired, wherein the preprocessed digital content files are downloaded and stored in an electronic device (such as a personal computer or a mobile phone) (step S12), and a DRM engine of the electronic device is triggered (step S13). Each of the preprocessed digital content files are bound with the rights objects and an International Mobile Equipment Identification (IMEI) code of the electronic device (step S14) and converted into a new file format using the DRM engine (step S15), which can only be accessed by the specific application.
The described method is applied to the Open Mobile Alliance (OMA) DRM process, the Windows Media DRM for Network Device (WMDRM-ND) process, and the Apple FairPlay™ process. With respect to the OMA DRM process, the original digital content files are provided with a file format, such as .3gp, .mp3, or the like. The OMA DRM process performs a preprocessing operation, such that the digital content files with the .3gp format are converted to the digital content files with the .dm format, representing DRM material files, and the digital content files with the .dm format are stored in a file server to be downloaded. When a user purchases the digital content files and receives rights objects (i.e. the digital content files), the digital content files with the .dm format are downloaded and stored in an electronic device owned by the user. A DRM engine of the electronic device binds the rights objects with an IMEI code of the electronic device and converts the digital content files with the .dm format to the digital content files with the .dcf format representing DRM Content Format files. Thus, the processed digital content files with the .dcf format can only be accessed by the electronic device or other specific electronic devices.
However, the described method can only be applicable to on-line transmissions and may violate Traditional Rights and Usage (TRU) of the digital content files for the user.
FIG. 2 is a flowchart of another conventional method for DRM processing.
Preprocessed digital content files are stored in an embedded memory of an electronic device such that the preprocessed files are encrypted (step S21). Rights objects for the digital content files are downloaded through a network (the internet, for example) (step S22) and are stored in the electronic device (step S23) and a DRM engine of the electronic device is triggered (step S24). The DRM engine decrypts the preprocessed digital content files (step S25), binds the rights objects and an IMEI code of the electronic device with each of the decrypted digital content files (step S26), and converts the digital content files into a new file format (step S27).
Thus, the converted digital content files can only be accessed by the electronic device, for example, the .asf (Advanced System Format) files accessed by the Windows Media DRM for Portable Devices (WMDRM-PD). The described method can be applicable to portable electronic devices and the rights objects are required to be separately transmitted, slightly enhancing security versus the previously mentioned method, but still reliant on network transmissions.
FIG. 3 is a flowchart of another conventional method for DRM processing.
An exclusive DRM engine or a DRM system is designed by the content owner himself (step S31). The digital content files are preprocessed and converted into a file format which can only be recognized by the exclusive DRM engine or the DRM system (step S32). Thus, the digital content files can only be accessed by an electronic device comprising the exclusive DRM engine or the DRM system (step S33). The described method may result in considerable workload, occupying a lot of memory space, compatibility issues between the DRM engine or the DRM system and an operating system of the electronic device, and distrust by content providers.